EFFECTS OF INJURY UPON SPERM. 25! 



where it is able to draw in the sperm head. In other cases the 

 sperm head enters and the rate may be increased greatly but not 

 enough to cause the normal completion of many processes. In 

 some cases the rate may be so low that cleavage cannot take place 

 in a normal manner. Since nearly all of the forms investigated 

 show r abnormalities at the period of gastrulation it may be that 

 the minimal rate necessary for normal gastrulation is often not 

 reached by the eggs in the experimental cultures. In Nereis at 

 the period of elongation fcllo\\ing the tro.h ->j: hore stage, there 

 is again a product'on of abnormalities in the posterior region. 

 Although the evidence is very fragmentary at present it seems 

 that the lack of specificity in these experiments is perhaps 

 capable of explanation upon the basis of lowered rate of metab- 

 olism produced by injury to the sperm. Farther research will 

 be necessary before w r e can do much more than venture a guess 

 as to the solution of the problem. 



We are safe in concluding from the observations upon man and 

 the higher mammals and from the experimental work upon mam- 

 mals, amphibians, annelids, echinoderms, and the higher plants, 

 that it is possible to injure the male germ cells by the application 

 of external forces so as to produce a change in the next generation 

 at least. We cannot say just how long this change may persist. 

 The work of Gager upon plants indicates that changes so pro- 

 duced may persist through several generations. Tower's work 

 upon the female germ cells of Leptinotarsa indicates that the 

 changes may persist or may gradually fade away. In all proba- 

 bility the results obtained by the methods which I have used will 

 prove to be for the most part transitory, although there is no 

 reason to believe that some of them may not persist. 



There is, then, good reason to believe that some drugs, such as 

 alcohol and cocaine, are a detriment, not only to the consumer 

 but also under certain conditions to his offspring. Since alcohol 

 appears in the seminal fluid very shortly after being taken into 

 the stomach, there is good reason to believe that a man, intoxi- 

 cated for the first time, even, may beget offspring which will be 

 in some degree defective. It is also possible, though not demon- 

 strated, that, in addition to drugs taken voluntarily into the 

 system, the products of abnormal metabolism may exercise g. 



